1. Technical Field
The present invention relates to setting the respective positions of ink keys in an ink fountain of a printing unit.
2. Background Art
Different ways of setting ink keys in an ink fountain of a printing unit are known. One way to set the ink keys is to move each ink key with an associated actuator. Each ink key is associated with a portion of a doctor blade. The portions of the doctor blade are associated with portions of an ink roll and may be positioned to form a gap between the ink roll and the doctor blade.
When the ink roll rotates, a thin film of ink forms on the ink roll. The thickness of the thin film of ink formed on different portions of the ink roll depends upon the size of the gap between the portions of the doctor blade and the associated portions of the ink roll. The size of the gap varies as a function of the positions of the portions of the doctor blade relative to the associated portions of the ink roll. The position of each portion of the doctor blade relative to its associated portion of the ink roll can be changed by adjusting the ink key associated with the particular portion of the doctor blade. Thus, the thickness of the thin film of ink formed on different portions of the ink roll can be changed by adjusting the ink keys.
The ink keys are typically adjusted manually by a human operator when the printing unit is in a maintenance mode. Typically, each ink key may be adjusted by manually turning a knurled head or the like on the ink key. Also, typically, each ink key may be adjusted by actuation of a bidirectional motor which drives the ink key. While the past practices have been reasonably satisfactory, there is a need for an improved ink key adjustment mechanism.